Gripper for printing presses



R.- T. SNELL.

GRIPPER FOR PRINTING PRESSES.

APPLICATION FILED DEC. I0, I920- 1,405,949, Patented Feb. 7, 1922.

7 2 SHEETSSHEET I- Zv/E/v 727/? R. T. SNELL.

GRIPPER FOR PRINTING PRESSES.

APPLICATION FILED DEC.10, 1920.

1,405,949; Patented Feb. 7, 1922;

2 SHEETS-SHEET 2.

UNITED STATES ROBERT T. SNELL, OF CLEVELAND, OHIO.

GRITPER FOR PRINTING PRESSES.

Specification of Letters Patent.

Patented Feb. '7, 1922.

I Application filed December 10, 1920. Serial No. 429,675.

Z '0 all whom it may concern:

Be it known that I, Bonner T. SNELL, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented a certain new and useful Improvement in Grippers for PrintingPresses, of which the following is a full, clear, and exact description,reference being had to the accompanying drawings.

This invention relates to printing grippers adapted for holding a sheetof paper in position during the printing operation, and is primarilyconcerned with improvements in the means for retaining a sheet adjacentthe platen of a printing press.

Some of the means now employed for retaining a sheet of paper inposition, embody adjustable rigid grippers having one or more fingersextending inwardly therefrom.

With the old form of grippers embodying fingers slidably mounted onrigid bars, I have found that it is diflicult to obtain accurate andminute adjustment of the fingers. Furthermore, the construction of thefingers has been more or less complicated and has required severalpieces to complete the entire device.

In a number 'of instances I have found that the fingers were unable tosecurely grip the sheet against the platen, and consequently air pocketshave been formed beneath the sheet during the printing operation; and asa result of such pockets the printing has' often been blurred.

An object of this invention is the provision of a finger particularlyadapted for effectively holding a sheet against the platen during theprinting operation and for'preventing the formation of air pocketsbeneath the sheet. I

Another object is the provision of a printing gripper having meansthereon for readily adjusting the gripping mechanism and for enabling anoperator to render accurate and minute adjustments in a minimum of time.

Still another object is the provision of a gripper finger that is light,yet strong in construction, and which is free from sharp projections onthat portion thereof which may be engaged by the hands or clothes of anoperator.

In accomplishing the above objects I prefer to employ a gripper barhaving sawteet-h serrations, and adapted to support fingers which areslidably mounted thereon.

The particular method of constructing the shdable fingers together withthe method of supporting them on the bar constitute the novel featuresof my invention. These features will be more fully described in detail,

in connection with the accompanying drawings, and the essentialcharacteristics thereof will be set forth in the claims.

In the drawings Fig. 1 is a side elevation of a ob printing press,having my invention applled thereto; Fig. 2 is a plan of a platen withthe-grippers in position above a sheet prior to the printing operation;Fig. 3 is an enlarged plan of a gripper bar'having adustable fingersmounted thereon; Figs. 4:, 5 and 6 are details showing the manner ofconstruction of the gripper finger. In F 1g. 1 is shown ajob press,which is illustrative of any form'of printing press with which myinvention may be employed. In this view, A indicates a side frame'membercarrying the usual platen B, and equipped with any suitable mechanismnot shown, for presenting theplaten to the type D. The usual rotaryinking plate is illustrated at F, which in addition to the type andassociated mechanism is carried on a pivoted frame G. This frame isoperated by the ordinary connecting link K between the frame and thecrank pin on the gear L. The

gripper is represented generally at M, and is provided with means, notshown, for bringing it into contact with the paper as the platen islowered, and brought into contact with the type D.

Designating the parts shown in the draw- 1ngs by the use of referencenumerals, in Fig. 3, 10 designates a form of gripper bar, adapted foruse with my invention. This bar comprises a narrow strip of materialprovided with an aperture at 11 for securing the inner end thereof to aplaten, and provided with an arm extending upwardly therefrom, an amountsufficient to gri the longest sheet of which the press unc erconsideration is capable of handling. One side 12 of the bar is smooth,while the other side thereof is provided with saw-teeth serrations 13extending nearly the entire length of the bar. .The extreme end of thebar is rounded, as at 14, to present a comparatively smooth surface tothat portion which is adjacent the operator of the printing press. Theseserrations may have a pitch, which can be varied in accordance with thedegree of accuracy in adjustment required, and the points of the teethmay be hardened to provide a durable wearing surface.

When the bars are mounted on the platen they are positioned as shown inFig. 2, where the smooth sides 12 face inwardly and are.

7 one end 16 of the platen B and feeds the sheets, one at a time,against the stops 17 at the other end thereof.

To retain the sheet securely against the platen, I provide one or morefingers, which are slidably mounted on the gripper bar, and are providedwith retaining means for securely holding the finger at any desiredposition. Each finger comprises a strip 20 of thin material, preferablymetal, which may be pressed and formed to provide an opening, throughwhich the gripper bar is adapted to slide. I prefer to construct eachfinger as shown in Figs. f to 6 from a metal stamping and to fold aportion of the metal backwardly upon itself, and securely fasten it insuch folded position. 7

In Fig. 4 I have shown a blank form having the projecting finger 20 andthe body portion 21. In the body portion suitable notches as at 22 arecut toprovide laterally extending tongues 23, and at one end of the bodyportion I'p'rovide notches 24, together with a projecting strip ortongue 25. Aligned with the tongue 25 and at the other end of the bodyportion I provide a notch 26, which extends through the metal and'is ofa size sufficient to permit the tongue 25 to be inserted therethrough.It will be noted that the various notches andtongues may be stamped inone operation from a blank form, and that the blank may be folded asshown in Figs. 5 and 6 to form a complete finger. During the foldingprocess,

the tongues 23 are bent inwardly at an angle that is substantially equalto the face angle of the saw-teeth serrations on the gripper bar.

In Fig. 6 the tongue 25'is shown as extending through the body portion,and is riveted to the other side thereof. The point at which the tongueis riveted is so positioned with relation to the "arcuate portions '27that the cross-sectional area between notch 26 and each arcuate portion,is substantially equal to the cross sectional area of the finger 20.This, of course, provides strength at a point where the greatest strainis liable tobe exerted upon the projecting member.

The construction of a slidable finger from a one-piece form permits thisdevice to be uickly constructed and cheaply assembled.

he-projectingfingers may be tempered so against the gripper bar, Iprefer to use a leaf spring 28, which extends from one end of the fingerto the other end thereof through the notches'2ei. The elasticity of thespring is suflicient to retain it in position without the use of otherretaining means, such as rivets. We prefer to position the spring in thefinger by having the ends 29 thereof, in abutting engagement with thesurface 12 of the bar, and by having the center position thereofintertwined between the notches 24;.

In operation a pair'of gripper bars are secured to the platen, with thesmooth sides 12 facing inwardly. Thes'e bars are positioned apart anamount sufficient to permit a sheet 15 to be inserted between them, andthen a suitable number of fingers are slipped over the bar and adjustedinto position between the type. Various lengths of fingers are providedto correspond with the type used, and with the size of sheet to beretained. To adjust the fingers, the operator 1 manually presses thebody portion thereof, against the tension in the spring'28, until thetongues 23 clear the points of the serrations 13. Then the fingers maybe slid lengthwise of the bar and the pressure released, whereupon'thetongues will again engage the serrations and be securely held againstthe bar. V 7

From the foregoing description it will be seen that I have provided agripper which is capable of being adjusted to'a fine degree of accuracy,and efliciently holds the paper against the platen; and which isequipped with a form of bar that enables one to opcrate. a press withoutendangering'either detents disposed in opposite directions and inengagement with the-serrated portion of I the bar, said detents beingdisposed adjacent the ends of the body portion and formed integraltherewith, said body portion having notches adjacent the smooth side ofthe bar, and a spring intertwined between said notches for holdin thedetents in engagement with the bar, sai spring having the ends thereofin abutting engagement with said bar.

2.1n'oombination, a gripper bar having a series of sawtooth serrationsalong one side thereof, a finger slidably mounted on the bar, saidfinger comprising a one-piece construction having a body portion and anextended portion, the body portion having detents integral therewith anddis osed in opposite directions from the ends t ereof, a springinterwoven in the body portion in such. manner that the ends of thespring are in sliding contact with the bar, whereby both of said detentsare held with approxiigiately equal force in engagement with said ar. v

3. In combination, a gripper bar having serrations along one sidethereof, a member comprising a one-piece structure having a portionthereof embracing the bar, and having two inwardly inclined andoppositely disposed detents arranged to engage one side of said bar, andhaving two approximately parallel apertures adjacent the other side ofsaid bar, and a spring interwoven through said apertures in such mannerthat the middle portion of the spring is on the exterior part of thebody portion, while the ends of the spring are on the interior partthereof,

whereby the points of contact between the spring'and bar aresubstantially in a plane with the points of engagement between thedetents and bar, said plane being substantially normal to the plane ofthe bar.

4. In combination, a gripper bar havin saw-tooth serrations on one sidethereof, an a smooth surface on the other side thereof, a gripperfinger, said finger having a onepiece body portion embracing the bar,said body portion being bent inwardly to form a detent, and a springcarried by the body portion for normally urging the detent intoengagement with the bar, said spring being retained in position by beinginterwoven in the body portion of said finger.

In testimony whereof, I hereunto aflix my signature.

ROBERT T. SNELL.

